“It was a pretty big umbrella to fill,” says Carter Bays of finding an actress to play the titular mother. “And yet Cristin is, against all odds, exactly what we were looking for. She made us laugh on 30 Rock, she made us swoon in Once, and her ukulele skills are no joke.”

Milioti’s season-ending cameo was shot on March 27 on the Twentieth Century Fox lot in Los Angeles. Strict non-disclosure agreements and a (mostly) closed set were just a few of the precautions taken to preserve the surprise.

Bays says viewers will become “much better” acquainted with Milioti’s character during the comedy’s ninth and final season, which, he teases, “will tell the epic story of the longest wedding weekend ever.”